RHEOLOGICAL BEHAVIOUR OF ETHYLENE GLYCOL BASED TITANIA

NANOFLUIDS

KHAIRUNNISA BINTI ABDUL HALIM

A project report submitted in partial fulfilment of the

requirements for the award of the degree of

Bachelor of Engineering (Chemical)

Faculty of Chemical Engineering

Universiti Teknologi Malaysia

JANUARY 2013

v

ABSTRACT

The purpose of this study is to investigate the rheological behaviour of

ethylene glycol (EG) based titania nanofluids. Generally, rheology is the study of

the deformation and flow of the matter. Nanofluids are dilute liquid suspensions of

nanoparticles which at least one critical dimension smaller than ~100nm in which is

used to enhance the thermal heat coefficient. Nanofluids have better heat

characteristics and have larger thermal conductivities compared to the base fluids,

however, the thermal behaviour of nanofluids correlates well with the rheological

behaviour of the nanofluids. This indicates the significance of studying the rheology

of nanofluids. In order to study the rheology of nanofluids, a set of stable nanofluids

have to be prepared with several different concentration and pH value. Then the

characterization of nanofluids will be done in terms of stability and viscosity; at

different temperature (27 ⁰C, 40 ⁰C, 50 ⁰C and 60 ⁰C); and concentration of titania

nanoparticles. Later the viscosity of the nanofluids were analysed to understand the

rheology. Titania nanoparticles were dispersed in the EG as the base fluid by two-

step method. A surfactant, Sodium Lauryl Sulphate (SLS) was used to stabilize the

nanofluids. SLS surfactant helps to reduce agglomeration in the titania nanofluids.

From the observation, the samples were stable for not more than a week. For both

pH of titania nanofluids (pH 3 and pH 11), the viscosity was increasing with the

increment of weight percentages and decrease with the temperature. Furthermore,

the shear stress decreases with the temperature and increases with weight percentage.

vi

ABSTRAK

Tujuan kajian ini adalah untuk menyiasat kelakuan rheologi bendalir-

nano titania berasaskan glikol etilena (EG). Secara umumnya, rheologi adalah

kajian terhadap perubahan dan aliran sesuatu jisim. Bendalir-nano adalah

cairan cecair nanopartikel yang mengandungi sekurang-kurangnya satu

dimensi kritikal yang lebih kecil daripada ~100nm yang mana digunakan

untuk meningkatkan pekali haba terma. Bendalir-nano mempunyai sifat-sifat

haba yang lebih baik dan mempunyai pekali terma yang lebih besar jika

dibandingkan dengan bendalir asas. Walau bagaimanapun, perlakuan terma

bersangkut paut dengan perlakuan rheologi bagi cecair nano. Hal ini

menerangkan kepentingan kajian terhadap perlakuan rheologi cecair nano.

Untuk menyiasat perlakuan rheologi tersebut, satu set sampel titania-EG

cecair nano perlu disediakan dengan beberapa kepekatan titania nano-partikel

yang berbeza, pH dan suhu yang berbeza (27 ⁰C, 40 ⁰C, 50 ⁰C and 60 ⁰C).

Kemudian, pencirian cecair nano dilakukan dalam bentuk kestabilan dan

kelikatan; pada suhu dan kepekatan berbeza. Partikel-nano dari titania telah

diserakkan di dalam EG sebagai cecair dasar oleh kaedah dua langkah. Satu

bahan penyelerak, Sodium Lauril Sulfat (SLS) telah digunakan untuk

menstabilkan bendalir-nano. SLS membantu untuk mengurangkan

penumpuan dalam bendalir-nano titania. Melalui pemerhatian yang

dijalankan, bendalir-nano dari cairan EG stabil hanya untuk tidak lebih dari

satu minggu. Bagi kedua-dua nilai pH untuk bendalir-nano titania (pH 3 dan

pH 11), kelikatan telah meningkat dengan kenaikan peratusan berat dan

penurunan dengan. Tambahan pula, tegasan ricih berkurangan dengan suhu

dan meningkat dengan peratusan berat.

vii

TABLE OF CONTENT

CHAPTER TITLE

DECLARATION

PAGE

ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENT vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF ABBREVIATIONS xv

LIST OF SYMBOLS xvii

LIST OF APPENDIX xviii

1 INTRODUCTION

1.1 Background of Study 1

1.2 Problem Statement 4

1.3 Objective of Study 6

1.4 Scope of Study 6

1.5 Significant of Study 6

2 LITERATURE REVIEW

2.1 Rheological Behavior of Nanofluids 8

2.2 Experimentally Measured Rheological Data for

Nanofluids

11

viii

2.2.1 Effects of Newtonian and non-Newtonian

Behaviour

12

2.2.2 Effects of High Shear Viscosity 14

2.2.3 Effects of Shearing Time 18

2.3 Nanofluids 20

2.3.1 Properties of Nanofluids 20

2.3.2 Preparation of Nanofluids 21

2.3.3 Addition of Surfactant 22

2.3.4 Effects of Base Fluids on the Heat Transfer

Properties

23

2.4 Viscosity of Nanofluids 24

2.5 Factors that Affects Viscosity of the Nanofluids 25

2.5.1 Temperature 25

2.5.2 Weight Fraction 28

2.5.3 Particle Size and Shape 30

2.6 Stability Investigation 30

3 METHODOLOGY

3.1 Materials 33

3.2 Experimental Procedures 34

3.2.1 Preparation of Nanofluids 34

3.2.2 Stability Investigation 36

3.2.3 Viscosity Measurement 36

3.3 Process Flow Diagram 37

4 RESULT AND DISCUSSION

4.1 Introduction 39

4.2 Result and Discussion 39

4.2.1 Synthesis of EG based Titania Nanofluids 40

4.2.1 Stability Investigation 41

4.2.3 Factors that Affected Viscosity of Nanofluids 44

4.2.3.1 Wt% of TiO2 Nanoparticles 44

ix

4.2.3.2 Temperature 58

4.2.4 Rheological Behavior of EG based Titania

Nanofluids 65

4.2.4.1 Effects of Newtonian and non-

Newtonian Behavior 65

4.2.4.2 Effects of Shearing Time 71

5 CONCLUSIONS AND RECOMMENDATIONS 75

REFERENCES 77

APPENDIX 89

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